Enzymatic Hydrolysis of Proteins from Crustaceans of the Barents Sea

Enzymatic preparations from king crab hepatopancreas were shown to be capable, in principle, of producing protein hydrolysates. Hydrolysis of protein-containing waste of deep-water prawn and king crab occurs most successfully at pH 8.0–8.5 and 50–55°C for 5–6 h in the presence of 6 g enzyme per kg substrate. The total chemical composition of the hydrolysates, the molecular weight distributions of proteins and polypeptides, and the contents of free amino acids were studied in dry hydrolysates.     

Evaluation of genetic variability of the Kamchatka crab Paralithodes camtschaticus (Tilesius) using allozyme markers

Interspecific genetic variation in populations of red king crab Paralithodes camtschaticus Tilesius (Litholidae, Decapoda: Crustacea) was examined using allozyme markers. The activity of 57 enzymes and the general protein presumably encoded by 92 loci was detected. The level of allozyme variability was low: the expected heterozygosity and the proportion of polymorphic loci were respectively 0.027 +/- 0.008 and 6.5%. This level of heterozygosity is three times lower than the average value for 122 crustacean species (0.082 +/- 0.007). Although genetic variants were found at 22 loci, their frequencies were generally low: only in loci 6-Pgd, Alp-1, and Pep-1 did the frequencies of the most common alleles not exceed 0.9. All polymorphic loci except one had two alleles; the exception was 6-Pgd, which had three alleles. The possible reasons for the low level of allozyme variability in red king crab are discussed.     

Salinity tolerance of adult and juvenile red king crabs Paralithodes camtschatica

• 1.1. Juvenile king crabs were more tolerant of reduced salinities than adult crab; juvenile crab were better volume regulators at reduced salinities than adult crab.
• 2.2. Adult female king crab hemolymph was hyperosmotic to full seawater (30 ppt) and isosmotic to dilute seawater. Juvenile king crab (2 years old) were hypoosmotic at the same concentrations.
• 3.3. Lower osmotic concentration of juvenile hemolymph is at least partially due to lower sodium concentration.
• 4.4. Juvenile king crab can tolerate some dilution and survive for short periods in the reduced salinity of the lower intertidal zone.

     

Red king crab (<Emphasis Type="Italic">Paralithodes camtschaticus</Emphasis>) fisheries in Russian waters: historical review and present status

The red king crab (Paralithodes camtschaticus) is a highly valued delicacy on the international market and currently contributes significantly to the income from fisheries in the regions where it is harvested. Russian income from red king crab export is $200–250 million per year. We review both the biology and fishery of the two largest populations of this species in Russia, i.e., in western Kamchatka (Sea of Okhotsk) and in the Barents Sea. The latter was established in the mid-1990s after introduction of red king crab to the area in the 1960s. The Barents Sea crabs are larger, grow faster and mature earlier than the crabs from the Sea of Okhotsk owing to more favorable temperature conditions in the Barents Sea. Additionally, we provide fishery information for the Prymorie population of red king crab (Sea of Japan) that remains depressed and closed for commercial fishery at present. Although the fishery period of red king crab in western Kamchatka is much longer than in the Barents Sea (1930–present time vs. 2004–present time), similar patterns were observed for the exploited king crab populations. High annual landings led to a pronounced decrease in population density and total abundance that, in turn, led to closures or some limitations of fisheries. Subsequent rehabilitations of the populations provided an opportunity for reopening of the fisheries and further exploration of red king crab populations under sustainable management. The main reason explaining a decline in red king crab populations both in the North Pacific and in the Barents Sea is high, mainly illegal, fishing pressure. Sustainable harvest strategies for the fisheries could prevent negative scenarios (overfishing) in the future.     

Proteolysis in vitro as the Way of Modification of the Protein Trophic Component

The protein hydrolysates of two types, fodder and for microbiological medium, have been obtained in vitro, using protein containing wastes of Iceland scallop fishery (WSF) and enzyme preparation from the red king crab hepatopancreas. The degree of protein degradation and composition of obtained hydrolysates were analyzed. Intensive protein hydrolysis was necessary to obtain the microbiological diagnostic cultural media that fit trophic requirements for 12 microbial test-cultures. Addition of the fodder protein hydrolysate to diet of juvenile salmons Salmo salar during mixed feeding produces a positive effect on their survival; the 5 and 20% replacement of fish flour by the fodder hydrolysate results in a reduction of fish mortality by 21 and 57%, respectively. The living weight of chickens increased by 15% after substitution of the 10% fish flour by the fodder WSF hydrolysate in their diet. The results obtained can be explained by a more effective assimilation of partly hydrolyzed proteins in comparison with native ones.     

Development of microsatellite loci in red king crab (Paralithodes camtschaticus)

Polymerase chain reaction (PCR) primers for three trinucleotide and three tetranucleotide microsatellite loci were developed for red king crab (Paralithodes camtschaticus) to aid in studies of genetic population structure in Alaskan waters. Number of alleles ranged from six to 18 alleles (N = 562), and locus heterozygosities ranged from 0.505 to 0.839. Six primers were cross amplified with golden king crab (Lithodes aequispinus); five primers with blue king crab (P. platypus); and one primer with the splendid hermit crab (Labidochirus splendescens), the ‘missing link’ between pagurid and lithodid crabs. No cross amplification occurred with Tanner crab (Chionoecetes bairdi) or Aleutian hermit crab (Pagurus aleuticus).     

Impact Scenario for an Introduced Decapod on Arctic Epibenthic Communities

The intentional introduction of a species for the enhancement of stock or establishment of new fisheries, often has unforeseen effects. The red king crabs, Paralithodes camtschaticus, which was introduced into the Barents Sea by Russian scientists, has established a self-sustaining population that has expanded into Norwegian waters. As top benthic predators, the introduced red king crabs may have possible effects upon native epifaunal scallop (Chlamys islandica) communities. These benthic communities may be a source of prey species in late spring, when the red king crabs feed most intensively. Foraging rates (consumption, killing or severely damaging) of red king crab on native prey organisms were measured by factorial manipulation of crab density (0.5, 1.5 and 3 per m ²), size classes (immature, small mature, and large mature crabs), and by evaluating prey consumption after 48 h, in order to extrapolate a scenario of the likely impacts. Foraging rates of the red king crab on scallops ranged between 150 and 335 g per m² within 48 h. These rates did not change when crab density was altered, though an increased amount of crushed scallops left uneaten at the tank floor, were correlated with high density of small mature crabs. Foraging rate changed significantly with crab size. Consequently, the susceptibility of native, shallow water epibenthic communities to red king crab predation in the early life history stages, and during the post-mating/molting spring period, must be considered significant when foraging rates are contrasted with natural scallop biomass between 400 and 1200 g scallops per m².     

Distribution of neurons containing catecholamines in brain of hermit crab <Emphasis Type="Italic">Pagurus middendorffii</Emphasis> and of king crab <Emphasis Type="Italic">Paralithodes camtschaticus</Emphasis> (Anomura,Decapoda)

Distribution of catecholamine-containing neurons in the brain of two species of crustaceans—hermit crab Pagurus middendorffii and the king crab Paralithodes camtschaticus was studied by immunocytochemical methods using an antibody against tyrosine hydroxylase (TH). In both species of the studied crustaceans, morphologically different types of TH-immunoreactive neurons are detected in cell clusters in brain protocerebrum, deutocerebrum, and tritocerebrum. Similarities and differences in the topography, numbers, and morphology of TH-positive neurons in different brain structures in the hermit crab and king crab are discussed.     

On the growth of the blue king crab (<Emphasis Type="Italic">Paralithodes platypus</Emphasis>) population in the Peter the Great Bay of the sea of Japan

The causes of the appearance of large blue king crabs (Paralithodes platypus) in Peter the Great Bay for the last decade are discussed. This species is an important commercial resource in the waters of Russian Far Eastern seas, and its general concentrations are related mainly to the sublittoral and upper bathyal zones of the northwestern Bering Sea and the northern Sea of Okhotsk. Until recently, this species has been observed in areas along the continental coast of the northwestern Sea of Japan up to the Peter the Great Bay, where it incidentally showed up in red king crab (P. camtschaticus) and snow crab (Chionoecetes opilio) catches but was also commercially used. This area was considered as the southern periphery of the species range. Since the late 1990s, both male and female blue king crabs have been recorded in trawl and trap catches during research works conducted within the Peter the Great Bay. Since 2002, any commercial catches of shelf crab species are prohibited in the waters south of 47°20′ N because of a dramatic decline in their populations. Since then all the illegally caught crabs, including blue king crabs that are seized live from poachers, are released back into the water in certain places of the bay. In total, at least 29 503 blue king crabs, including egg-bearing females, were released within the period from 2002 to November 2009. At present, the overall blue king crab abundance in Peter the Great Bay, estimated based on the trap catches over an area of 7048 km², is 50500, the abundance of commercial-size males (with a carapace width over 130 mm) is 7500, and the male to female ratio is 1.00: 1.35. The increase in the blue king crab population observed in the bay is the result of the immigration of mature and viable individuals from other areas of its range. After this “uncontrolled introduction” blue king crabs adapted to new conditions, and then began breeding and spreading over the entire area of the bay.     

The Current Status of the Red King Crab (Paralithodes camtschaticus) Stock and Fishery off Western Kamchatka

Russian Journal of Marine Biology - The current status of the red king crab population off western Kamchatka is considered based on data from bottom trawl surveys and fishery statistics since 2013....     

First observations of temperature tolerances of adult male snow crab (Chionoecetes opilio) from the Barents Sea population and the effects on the fisheries strategy

This study investigates the effects of temperature on the survival, food intake, oxygen consumption and growth during long-term live holding of captive male snow crab (Chionoecetes opilio) (average?=?0.7?kg). The crabs were held at three different temperatures, 3, 6 and 9°C. The trials were done using groups of snow crabs held in nine land-based holding tanks (three replicates per temperature treatment). The results showed that temperature had a significant effect on survival. The survival rate at 3°C (61%) was significantly higher than at 6°C (33%) and at 9°C (28%). Specific oxygen consumption rates of unfed crab at 6°C were significantly higher than at 9°C and 3°C. In summary, the current study shows that the Barents Sea snow crab have a narrow temperature range in which they thrive compared with the Barents Sea red king crab (Paralithodes camtschaticus). Barents Sea snow crab has similar metabolic and physiological attributes to other major snow crab populations. In conditions when ambient temperatures are approximately 6°C, it may prove beneficial for animal welfare and also be financially advantageous to reduce ambient water temperatures in live snow crab holding facilities on boat or on land.     

Isolation and primary structure of trypsin from the red king crab Paralithodes camtschaticus

Trypsin from hepatopancreas of the Paralithodes camtschaticus crab was isolated in homogeneous state by successive ion-exchange chromatography on DEAE-Sephadex, affinity chromatography on Agarose modified with peptide ligands from trypsin hydrolysate of salmin, and ion-exchange chromatography on a Mono Q column. The total yield of the protein was 64%. Its N-terminal amino acid sequence was determined (IVGGTEVTPG-). A sample of amplified total cDNA of hepatopancreas of king crab was obtained. The cDNA fragment containing the complete coding part of the gene was isolated on the basis of the known N-terminal amino acid sequence of the mature form of the trypsin. The polypeptide chain of the proenzyme consists of 266 aa. The mature trypsin involves 237 aa, which corresponds to its molecular mass of 24.8 kDa. A comparison of the amino acid sequence of the king crab trypsin with those of trypsins from other species of crustaceans demonstrated their high structural homology. The trypsin from the Penaeus vannamei shrimp appeared to be the most close in its primary structure to that of the king crab (70% identity).     

Post-settlement effects of habitat type and predator size on cannibalism of glaucothoe and juveniles of red king crab Paralithodes camtschaticus

Postlarval (glaucothoe) and juvenile (first crab stage, C1) red king crab Paralithodes camtschaticus actively select structurally complex substrata for settlement. Such habitats may provide them with shelter from predation during critical early stages. We tested this hypothesis by placing glaucothoe and juvenile crab in aquaria with or without natural or artificial habitats, and with or without predators (1-3-year-old red king crab) of two different sizes. Predators caused increased mortality of glaucothoe, but predator size, habitat presence and habitat type had no effect on survival. Predators caused significant mortality of C1 crabs in the absence of habitat, and mortality was inversely related to predator size. Density of glaucothoe on habitats was similar with or without predators, but density of C1 crab on habitats was higher than that of glaucothoe, and increased in the presence of large predators. Active selection for complex substrata by settling glaucothoe does not reduce cannibalism, but may pre-position them for improved survival after metamorphosis. In contrast, juvenile crabs modify their behavior to achieve higher densities in refuge habitats, which tends to dampen the effect of predation. These survival strategies may have evolved to compensate for the greater risk of predation in open habitats.     

Effects of Ocean Acidification on Juvenile Red King Crab (Paralithodes camtschaticus) and Tanner Crab (Chionoecetes bairdi) Growth,Condition, Calcification,and Survival

Ocean acidification, a decrease in the pH in marine waters associated with rising atmospheric CO₂ levels, is a serious threat to marine ecosystems. In this paper, we determine the effects of long-term exposure to near-future levels of ocean acidification on the growth, condition, calcification, and survival of juvenile red king crabs, Paralithodes camtschaticus, and Tanner crabs, Chionoecetes bairdi. Juveniles were reared in individual containers for nearly 200 days in flowing control (pH 8.0), pH 7.8, and pH 7.5 seawater at ambient temperatures (range 4.4–11.9 °C). In both species, survival decreased with pH, with 100% mortality of red king crabs occurring after 95 days in pH 7.5 water. Though the morphology of neither species was affected by acidification, both species grew slower in acidified water. At the end of the experiment, calcium concentration was measured in each crab and the dry mass and condition index of each crab were determined. Ocean acidification did not affect the calcium content of red king crab but did decrease the condition index, while it had the opposite effect on Tanner crabs, decreasing calcium content but leaving the condition index unchanged. This suggests that red king crab may be able to maintain calcification rates, but at a high energetic cost. The decrease in survival and growth of each species is likely to have a serious negative effect on their populations in the absence of evolutionary adaptation or acclimatization over the coming decades.     

Properties of chitinolytic enzymes from the hepatopancreas of the red king crab (Paralithodes camtschaticus)

Our study confirms the presence of chitinolytic, chitosanolytic, and deacetylase activities in the hepatopancreas of the red king crab, related to the specific diet of this species. The maximum rate of chitin/chitosan hydrolysis by an enzyme preparation from crab hepatopancreas occurs at 36.5-37.0 degrees C. Two pH optimums have been found for the enzymatic reaction under mildly alkaline and acidic conditions for both exo- and endochitinase activities. The enzyme preparation is most affine to partly deacetylated chitin with an acetylation degree within 40-50%.     

Epibionts of the red king crab Paralithodes camtschaticus (Tilesius, 1815) in Sayda Inlet of Kola Bay

The species composition of organisms associated with the red king crab Paralithodes camtschaticus (Tilesius, 1815) was investigated in Sayda Inlet of Kola Bay in 2004–2005. Nine fouler species and three symbiotic species were found on the carapaces of the red king crab. Balanus crenatus Bruigere 1789 barnacles were the most abundant fouler species and were found on 14.8% of the crabs. Symbiotic amphipods Ischyrocerus commensalis Chevreux, 1900 were found for one-tenth of all the crabs studied. The mean intensity of the amphipods was significantly greater for September, when the reproduction period of this species occurred. Male and female crabs were hosted with the same intensity. The number of host crabs increased accordingly to the crab size. The proportion of hosted crabs was three-fold less in Sayda Inlet than in the less polluted areas of the Barents Sea.     

Impact scenario for the invasive red king crab <Emphasis Type="Italic">Paralithodes camtschaticus</Emphasis> (Tilesius, 1815) (Reptantia,Lithodidae) on Norwegian,native, epibenthic prey

Large invasive predators like the king crab, Paralithodes camtschaticus, deserve particular attention due to their potential for catastrophic ecological impact on recipient communities. Conspicuous, epibenthic prey species, such as the slow growing commercial scallop Chlamys islandica, are particularly exposed to the risk of local extinction. A research program integrating experiments and field monitoring is attempting to predict and track the impact of invasive king crab on scallop beds and associated fauna along the north Norwegian coast. The claw gape of the crab shows no limitations in handling the flat-bodied scallop. However, the potential impact of the crab on scallop may depend on the availability of other calcified prey associated with scallop beds, such as the sea star, sea urchin, and blue mussel, all species recorded in the diet of P. camtschaticus. To address this issue, a laboratory experiment on foraging behaviour of P. camtschaticus was conducted. The experimental results show that all size classes of red king crab prefer scallops, but small juveniles and medium sized crabs demonstrate active selection for starfish (Asterias rubens) that equals or surpasses the electivity of the large crab. The selection of sea urchin (Strongylocentrotus droebachiensis) and blue mussel (Mytilus edulis) is slightly positive or neutral for the three crab size classes. These results suggest that scallop beds with a rich associated fauna are less vulnerable to red king crabs predation and possibly more resilient than beds with few associated species. Also, crab size distribution is likely relevant for invasion impact, with increasing abundance of small and medium sized crabs being detrimental for alternative calcified prey associated with scallop beds. Successive stages of crab invasion will see an acceleration of scallop mortality rates associated with (i) decreasing availability of alternative prey, due to protracted predation pressure intensified by recruitment of juvenile crabs, and (ii) increased number of large crabs. Estimates of crab density and intake rates suggest that the accelerated loss rates will eventually endanger scallop beds persistence.     

Isolation and Primary Structure of Trypsin from the King Crab Paralithodes camtschaticus

Trypsin from hepatopancreas of the crab Paralithodes camtschaticuswas isolated in homogeneous state by successive ion-exchange chromatography on DEAE-Sephadex, affinity chromatography on Agarose modified with peptide ligands from trypsin hydrolysate of salmin, and ion-exchange chromatography on a Mono Q column. The total yield of the protein was 64%. Its N-terminal amino acid sequence was determined (IVGGTEVTPG-). A sample of amplified total cDNA of hepatopancreas of king crab was obtained. A cDNA fragment containing the complete coding part of the gene was isolated on the basis of the known N-terminal amino acid sequence of the mature form of the trypsin. The polypeptide chain of the proenzyme consists of 266 aa. The mature trypsin involves 237 aa, which corresponds to its molecular mass of 24.8 kDa. A comparison of the amino acid sequence of the king crab trypsin with those of trypsins from other species of crustaceans demonstrated their high structural homology. The trypsin from the shrimp Penaeus vannamei appeared to be closest in primary structure to that of the king crab (65% identity).     

Microsporidia of the genera <Emphasis Type="Italic">Thelohania</Emphasis> (Thelohaniidae) and <Emphasis Type="Italic">Ameson</Emphasis> (Pereziidae) in two species of lithodid crabs from the Sea of Okhotsk

Diseases caused by microsporidia were found in the red king crab Paralithodes camtschaticus and the blue king crab P. platypus that inhabit the Sea of Okhotsk. Based on the histological features of the invasion and data on the morphological structure of the parasites, the microsporidia were assigned to the genera Thelohania and Ameson. Infected crabs exhibited severe destructive changes of their internal organs along with sharply pronounced external signs of disease. During the observation period, the microsporidian invasion was only found in females and young (unmarketable size) males from August to mid-October. Later, until mid-December, no diseased crabs were found.     

Ontogeny of light response in the early life history of the red king crab Paralithodes camtschaticus (Anomura: Lithodidae)

Phototactic responses of light-adapted zoeae IV, glaucothoe, and first stage juveniles of the red king crab to three intensities of white light were quantitatively measured under laboratory conditions. All stages observed were photopositive to all light intensities tested, except for late glaucothoe (10 days since moulting) which did not respond to light stimuli. Phototactic response changed in the early life history of the red king crab. The extent of photopositive movement decreased after each metamorphosis. Peak phototactic response in zoea IV were observed at a light intensity of 1.9 × 10¹³ q cm^-2 s^-1, in early glaucothoe at 1.1 × 10¹⁰ q cm^-2 s^-1 and in juveniles at 1.3 × 10⁹ q cm^-2 s^-1. The data on behavioural responses to light may provide a better understanding of the early life history, survival and recruitment of the red king crab and assist the development of feasible methods and techniques for aquaculture of this species.